Effects of irrigation water quality and soil type on the soil and plant associated microbiome, abundance, diversity and transferability of antibiotic resistance genes in Gram-negative bacteria

在气候变化的条件下，农业灌溉废水的再利用是节约用水和增加粮食产量的有效途径。基础设施投资导致许多国家从使用未经处理的废水灌溉转向使用处理过的废水灌溉。拟议研究单位的sp5将有助于验证以下假设：1)从土壤释放并被植物吸收的污染物的环境浓度高到足以选择抗生素耐药性并触发土壤和植物中的水平基因转移；2)土壤类型调节污染物的释放和相关的抗生素耐药性选择。在未经处理的废水灌溉了50 ~ 80年的Leptosols、Phaeozems和Vertisols中添加处理过的或未经处理的废水，对微生物群落组成和抗生素耐药基因（ARGs）丰度以及与革兰氏阴性菌相关的移动遗传因子（MGEs）的影响将在基于总群落DNA的联合培养和批量实验中进行测试。对于土壤样品的一个子集水平基因转移（HGT）率之间的革兰氏阴性细菌将被确定。分离的肠杆菌（SP 6）将被筛选是否存在可转移质粒。在卫星实验中，研究人员将携带不含抗生素抗性基因的InCP-1质粒的土壤细菌baylyacinetobacter BD413应用于不同处理的土壤中，28天后重新分离，并通过InCP-1质粒筛选获得性ARGs。植物与ARGs的选择和传播以及向食物链转移的相关性将在种植香菜（Coriandrum sativum）的整体“未受干扰”土壤柱联合试验中进行研究。sp5将评估根际和根际微生物群落组成、革兰氏阴性菌ARGs和MGEs的相对丰度以及革兰氏阴性菌的hgt率。SP 5为Phaeozem土壤的联合田间试验提供了相同的专业知识和技术，该土壤用未经处理的废水灌溉了80年，并种植了香菜，以便将实验室和温室的控制实验与现实世界的条件联系起来，特别是关于灌溉水质对层状圈细菌的影响，这在温室条件下很难研究（减少辐射和灰尘输入）。通过将其结果和专业知识与RU其他SPs的数据和知识联系起来，也通过集成数学模型（SP 7）， SP 5有助于对不断变化的废水灌溉系统中污染物，抗生素耐药性和病原体之间相互作用的机制理解。

The reuse of wastewater for irrigation in agriculture is an efficient way of saving water and increasing food production for a growing population under conditions of climate change. Investments in infrastructure cause a shift from irrigation with untreated wastewater to irrigation with treated wastewater in many countries. SP 5 of the proposed research unit will contribute to testing the hypotheses that i) environmental concentrations of pollutants released from soil and taken up by plants are high enough to select antibiotic resistance and trigger horizontal gene transfer in soils and plants and ii) the soil type modulates the release of pollutants and the associated selection of antibiotic resistance.The effect of the addition of treated or untreated wastewater to Leptosols, Phaeozems and Vertisols, that have been irrigated with untreated wastewater for >80 years, on the microbial community composition and the abundance of antibiotic resistance genes (ARGs) as well as mobile genetic elements (MGEs) associated with Gram-negative bacteria will be tested in a joint incubation and batch experiment based on total community DNA. For a subset of soil samples horizontal gene transfer (HGT) rates among Gram-negative bacteria will be determined. Isolated Enterobacteria (SP 6) will be screened for the presence of transferable plasmids. The mobilization of ARGs to InCP-1 plasmids due to selection by antibiotics and disinfectants added with wastewater and released from soil will be tested in a satellite experiment, in which the soil bacterium Acinetobacter baylyi BD413 carrying IncP-1 plasmids without antibiotic resistance genes will be applied to the differently treated soils, re-isolated after 28 days and screened for acquired ARGs by IncP-1 plasmids.The relevance of plants for the selection and spreading of ARGs and the transfer into the food chain will be investigated in the joint soil column experiment with monolithic “undisturbed” soil columns planted with cilantro (Coriandrum sativum). SP 5 will assess the microbial community composition in phyllosphere and roots/rhizosphere, the relative abundance of ARGs and MGEs of Gram-negative bacteria, and HGT-rates among Gram-negative bacteria.SP 5 contributes the same expertise and techniques to the joint field experiment with Phaeozem soil irrigated with untreated wastewater for >80 years and planted with cilantro in order to bridge controlled laboratory and greenhouse experiments to real world conditions, especially regarding the effects of irrigation water quality on phyllosphere bacteria, which are difficult to study under greenhouse conditions (reduced radiation and dust inputs).By linking its results and expertise to the data and knowledge of the other SPs of the RU also by means of the integrated mathematical model (SP 7), SP 5 contributes to a mechanistic understanding of interactions between pollutants, antibiotic resistance and pathogens in changing wastewater irrigation systems.